Hughes 269C N9277R accident near Howe, Texas

Probable cause

The improper execution of an autorotation following the loss of engine power, which resulted in an uncontrolled descent into terrain. Contributing to the accident was the flight instructor's lack of remedial action during the autorotation.

NTSB analysis

The flight instructor and student pilot were flying the helicopter near dusk about 1,100 ft above ground level (agl) when the instructor initiated a practice autorotation, by reducing the throttle to idle. The engine subsequently experienced a total loss of power; the instructor attempted to restart the engine, but, was unsuccessful. The student provided conflicting statements regarding who was controlling the helicopter during the autorotation and landing, but stated that he started the landing flare about 25 ft agl. He further stated that he did not think that the helicopter's descent had been sufficiently slowed before the helicopter impacted the ground. Upon impact, the tail boom partially separated and the helicopter rolled over, coming to rest on its right side.

Postaccident examination of the helicopter and engine did not reveal any mechanical malfunctions or anomalies that would have precluded normal operation. Impact damage precluded any functional testing of the engine and its components, and the reason for the reported loss of engine power could not be determined.

The pilot's flight manual stated that an engine restart should not be attempted below 2,000 ft agl, and that, below that altitude, the pilot should conduct a normal autorotation to landing. The manual also stated that the fuel boost pump should be activated before a practice autorotation. The fuel boost pump switch was found in the OFF position. The manual also states that rapid throttle reductions to full idle during flight shall not be conducted at any altitude to minimize the possibility of engine stoppage.

Text from the NTSB. Open the NTSB docket for CEN16FA315 for the full record.